The postmulti(1) command allows a Postfix administrator to manage multiple Postfix instances on a single host.

postmulti(1) implements two fundamental modes of operation. In iterator mode, it executes the same command for multiple Postfix instances. In life-cycle management mode, it adds or deletes one instance, or changes the multi-instance status of one instance.

Each mode of operation has its own command syntax. For this reason, each mode is documented in separate sections below.

A multi-instance configuration consists of one primary Postfix instance, and one or more secondary instances whose configuration directory pathnames are recorded in the primary instance's main.cf file. Postfix instances share program files and documentation, but have their own configuration, queue and data directories.

Currently, only the default Postfix instance can be used as primary instance in a multi-instance configuration. The postmulti(1) command does not currently support a -c option to select an alternative primary instance, and exits with a fatal error if the MAIL_CONFIG environment variable is set to a non-default configuration directory.

See the MULTI_INSTANCE_README tutorial for a more detailed discussion of multi-instance management with postmulti(1).

Perform the operation only for the instance with the specified name. You can specify either the instance name or the absolute pathname of the instance's configuration directory. Specify "-" to select the primary Postfix instance.

Assign the specified instance name to an existing instance, newly-created instance, or imported instance. Instance names other than "-" (which makes the instance "nameless") must start with "postfix-". This restriction reduces the likelihood of name collisions with system files.

Create a new Postfix instance and add it to the multi_instance_directories parameter of the primary instance. The "-Iname" option is recommended to give the instance a short name that is used to construct default values for the private directories of the new instance. The "-Ggroup" option may be specified to assign the instance to a group, otherwise, the new instance is not a member of any groups.

The new instance main.cf is the stock main.cf with the parameters that specify the locations of shared files cloned from the primary instance. For "nameless" instances, you should manually adjust "syslog_name" to yield a unique "logtag" starting with "postfix-" that will uniquely identify the instance in the mail logs. It is simpler to assign the instance a short name with the "-Iname" option.

If any of these pathnames is not supplied, the program attempts to generate the pathname by taking the corresponding primary instance pathname, and by replacing the last pathname component by the value of the -I option.

If the instance configuration directory already exists, and contains both a main.cf and master.cf file, create will "import" the instance as-is. For existing instances, create and import are identical.

import

Import an existing instance into the list of instances managed by the postmulti(1) multi-instance manager. This adds the instance to the multi_instance_directories list of the primary instance. If the "-Iname" option is provided it specifies the new name for the instance and is used to define a default location for the instance configuration directory (as with create above). The "-Ggroup" option may be used to assign the instance to a group. Add a "config_directory=/path" argument to override a default pathname based on "-Iname".

destroy

Destroy a secondary Postfix instance. To be a candidate for destruction an instance must be disabled, stopped and its queue must not contain any messages. Attempts to destroy the primary Postfix instance trigger a fatal error, without destroying the instance.

The instance is removed from the primary instance main.cf file's alternate_config_directories parameter and its data, queue and configuration directories are cleaned of files and directories created by the Postfix system. The main.cf and master.cf files are removed from the configuration directory even if they have been modified since initial creation. Finally, the instance is "deported" from the list of managed instances.

If other files are present in instance private directories, the directories may not be fully removed, a warning is logged to alert the administrator. It is expected that an instance built using "fresh" directories via the create action will be fully removed by the destroy action (if first disabled). If the instance configuration and queue directories are populated with additional files (access and rewriting tables, chroot jail content, etc.) the instance directories will not be fully removed.

The destroy action triggers potentially dangerous file removal operations. Make sure the instance's data, queue and configuration directories are set correctly and do not contain any valuable files.

deport

Deport a secondary instance from the list of managed instances. This deletes the instance configuration directory from the primary instance's multi_instance_directories list, but does not remove any files or directories.

assign

Assign a new instance name or a new group name to the selected instance. Use "-G -" to specify "no group" and "-I -" to specify "no name". If you choose to make an instance "nameless", set a suitable syslog_name in the corresponding main.cf file.

enable

Mark the selected instance as enabled. This just sets the multi_instance_enable parameter to "yes" in the instance's main.cf file.

disable

Mark the selected instance as disabled. This means that the instance will not be started etc. with "postfix start", "postmulti -p start" and so on. The instance can still be started etc. with "postfix -c config-directory start".

The default location of the Postfix main.cf and master.cf configuration files.

daemon_directory (see 'postconf -d' output)

The directory with Postfix support programs and daemon programs.

import_environment (see 'postconf -d' output)

The list of environment parameters that a Postfix process will import from a non-Postfix parent process.

multi_instance_directories (empty)

An optional list of non-default Postfix configuration directories; these directories belong to additional Postfix instances that share the Postfix executable files and documentation with the default Postfix instance, and that are started, stopped, etc., together with the default Postfix instance.

multi_instance_group (empty)

The optional instance group name of this Postfix instance.

multi_instance_name (empty)

The optional instance name of this Postfix instance.

multi_instance_enable (no)

Allow this Postfix instance to be started, stopped, etc., by a multi-instance manager.

postmulti_start_commands (start)

The postfix(1) commands that the postmulti(1) instance manager treats as "start" commands.

postmulti_stop_commands (see 'postconf -d' output)

The postfix(1) commands that the postmulti(1) instance manager treats as "stop" commands.

postmulti_control_commands (reload flush)

The postfix(1) commands that the postmulti(1) instance manager treats as "control" commands, that operate on running instances.

syslog_facility (mail)

The syslog facility of Postfix logging.

syslog_name (see 'postconf -d' output)

The mail system name that is prepended to the process name in syslog records, so that "smtpd" becomes, for example, "postfix/smtpd".

Available in Postfix 3.0 and later:

meta_directory (see 'postconf -d' output)

The location of non-executable files that are shared among multiple Postfix instances, such as postfix-files, dynamicmaps.cf, and the multi-instance template files main.cf.proto and master.cf.proto.

shlib_directory (see 'postconf -d' output)

The location of Postfix dynamically-linked libraries (libpostfix-*.so), and the default location of Postfix database plugins (postfix-*.so) that have a relative pathname in the dynamicmaps.cf file.